我有一系列起始位置来读取程序中每个婴儿节点的文件。我正在尝试让headnode发送位置以开始将文件读取到每个节点，然后让它们发回结果。
难以理解的是文件中的行没有完美的节点数，因此必须反复使用它们。为了实现这一点，我尝试使用for循环进行发送和接收，其中头节点发送文件中行数的消息，并且婴儿节点接收文件中行数的消息除以数量babynodes。
简单地说，它不适合我，我真的不知道该怎么做。
if(qNum == 1){ //If query Number is one
if(firstSource == 1){ //And the source is equal to 1
if(my_rank == 0){ // if this process is the head node
int startVal = 0; // declare variable for starting value
int z = 1; // declare variable to loop through baby nodes
for(int i = 1; i <= enronInfo[0]; i++){ // for # of lines in file
if(z == world_size){ // if process num equals largest process num reset to 1
z = 1;
}
startVal = getFseekVal(i, firstSource); //set the startVal to the value at location I in the array.
MPI_Send(&startVal, 1, MPI_INT, z, i, MPI_COMM_WORLD); //send a message to processor z with the startVal
}
MPI_Barrier(MPI_COMM_WORLD); //Don't know if this helps
if(my_rank != 0){ //if not the headnode
int startVal; // declare variable for starting value
for(int i = 0; i<=babyLoopSize; i++){ // for # of lines in processor divided by # of babynodes
MPI_Recv(&startVal, 1, MPI_INT, 0, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE); // receive a message with startVal from the headnode
}
}
MPI_Barrier(MPI_COMM_WORLD); // Don't know if this helps
}
}
#include <fstream>
#include <string>
#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int enronDSarr[39859], nipsDSarr[1499], kosDSarr[3429], nytDSarr[299999]; //containers for docstring values
string enronV = "/home/mcconnel/BagOfWords/vocab.enron.txt";
string nipsV = "/home/mcconnel/BagOfWords/vocab.nips.txt";
string kosV = "/home/mcconnel/BagOfWords/vocab.kos.txt";
string nytV = "/home/mcconnel/BagOfWords/vocab.nytimes.txt";
string enronDW = "/home/mcconnel/BagOfWords/docword.enron.txt";
string nipsDW = "/home/mcconnel/BagOfWords/docword.nips.txt";
string kosDW = "/home/mcconnel/BagOfWords/docword.kos.txt"; // Strings for locations of each file
string nytDW = "/home/mcconnel/BagOfWords/docword.nytimes.txt";
string enronDS = "/home/mcconnel/BagOfWords/docstart.enron.txt";
string nipsDS = "/home/mcconnel/BagOfWords/docstart.nips.txt";
string kosDS = "/home/mcconnel/BagOfWords/docstart.kos.txt";
string nytDS = "/home/mcconnel/BagOfWords/docstart.nytimes.txt";
int enronInfo[3], nipsInfo[3], kosInfo[3], nytInfo[3]; // Arrays storing first 3 lines of info from each DocWords file
int firstSource, secondSource, numTimes, qNum, wordLength;
string enteredWord;
char enteredWordChar[50];
int word2int(string fileLocation, string input){ // converts text from a file into a word count value
ifstream file;
file.open(fileLocation.c_str());
string word;
int i = 1;
int wordNum;
while(file.good()){
file >> word;
if(word.compare(input)== 0){
wordNum = i;
return wordNum;
}
i++;
}
return wordNum;
}
int getFseekVal(int docNumber, int sourceNumber){
if(sourceNumber == 1){
return enronDSarr[docNumber - 1];
}
else if(sourceNumber == 2){
return nipsDSarr[docNumber - 1];
}
else if(sourceNumber == 3){
return kosDSarr[docNumber - 1];
}
else{
return nytDSarr[docNumber - 1];
}
}
string int2word(string fileLocation, int wordInt){ // converts a word count value from a file into the actual text
ifstream file;
file.open(fileLocation.c_str());
string word;
int i = 1;
string retWord;
while(file.good()){
file >> word;
if(i == wordInt){
retWord = word;
return retWord;
}
i++;
}
return 0;
}
int getInfoDW(string fileLocation, int pos){ //imports an array of length 3 for each document's info in the docwords file
ifstream file;
file.open(fileLocation.c_str());
int word;
int i = 0;
int retWord;
while(file.good()){
file >> word;
if(i == 0 && pos == 0){
return word;
}
if(i == 1 && pos == 1){
return word;
}
if(i == 2 && pos == 2){
return word;
}
i++;
}
return retWord;
}
int getEnronDS(string fileLocation){ // imports array from Enron docstart file
int i;
int z = 0;
FILE *MyFile;
char line[25];
MyFile=fopen(fileLocation.c_str(), "r");
for(i = 0; i<39861; i++){
fscanf(MyFile, "%s", line);
if(i != 0 && i % 2 == 1){
enronDSarr[z] = atoi(line);
z++;
}
}
fclose(MyFile);
}
int getNipsDS(string fileLocation){ // imports array from NIPS docstart file
int i;
int z = 0;
FILE *MyFile;
char line[25];
MyFile=fopen(fileLocation.c_str(),"r");
for(i = 0; i<1500; i++){
fscanf(MyFile, "%s", line);
if(i != 0 && i % 2 == 1){
nipsDSarr[z] = atoi(line);
z++;
}
}
fclose(MyFile);
}
int getKosDS(string fileLocation){ // imports array from KOS docstart file
int i;
int z = 0;
FILE *MyFile;
char line[25];
MyFile=fopen(fileLocation.c_str(),"r");
for(i = 0; i<3430; i++){
fscanf(MyFile, "%s", line);
if(i != 0 && i % 2 == 1){
kosDSarr[z] = atoi(line);
z++;
}
}
fclose(MyFile);
}
int getNytDS(string fileLocation){ // imports array from NYT docstart file
int i;
int z = 0;
FILE *MyFile;
char line[25];
MyFile=fopen(fileLocation.c_str(),"r");
for(i = 0; i<300000; i++){
fscanf(MyFile, "%s", line);
if(i != 0 && i % 2 == 1){
nytDSarr[z] = atoi(line);
z++;
}
}
fclose(MyFile);
}
int getCurrentDS(int fileNumber, int documentNum){ //Will be used to return docstart byte value at document location
if(fileNumber == 0){
return enronDSarr[documentNum - 1];
}
if(fileNumber == 1){
return enronDSarr[documentNum - 1];
}
if(fileNumber == 2){
return enronDSarr[documentNum - 1];
}
if(fileNumber == 3){
return enronDSarr[documentNum - 1];
}
else{
printf("Something definitely went wrong");
}
}
int getSourceNumber(){
int source;
printf("Select a wordbag:\n 1. Enron \n 2. NIPS \n 3. KOS\n 4. NYT\n");
cin >> source;
return source;
}
int getUserResponse(){
int i = 1;
while(i){
printf("Choose a query(1-4) and press enter:\n");
printf("1. What percent of documents in X use any one word more than ____ times?\n");
printf("2. What words in X are used more than ____ times in any document?\n");
printf("3. In which data set does the word ____ appear most frequently?\n");
printf("4. Does ____ appear more frequently in X or Y?\n");
cin >> qNum;
if(qNum < 5 && qNum > 0){
i = 0;
printf("%d", qNum);
}
else{
printf("Invalid Response, Please Try Again \n");
}
if(qNum == 1){
firstSource = getSourceNumber();
printf("and how many times?\n");
cin >> numTimes;
// query1(firstSource, numTimes);
}
else if(qNum == 2){
firstSource = getSourceNumber();
printf("and how many times?\n");
cin >> numTimes;
}
else if(qNum == 3){
printf("What word would you like to use?\n");
cin >> enteredWord;
}
else if(qNum == 4){
printf("What word would you like to use?\n");
cin >> enteredWord;
printf("Select your first source...\n");
firstSource = getSourceNumber();
printf("Select your second source...\n");
secondSource = getSourceNumber();
}
}
}
void importFiles(){
getEnronDS(enronDS);
getNipsDS(nipsDS);
getKosDS(kosDS); // Functions to read in arrays for each docstart fil
getNytDS(enronDS);
for(int a = 0; a <= 2; a++){
enronInfo[a] = getInfoDW(enronDW, a);
nipsInfo[a] = getInfoDW(nipsDW, a);
kosInfo[a] = getInfoDW(kosDW, a);
nytInfo[a] = getInfoDW(nytDW, a);
}
}
int main(int argc, char** argv){
int world_size, my_rank, numDocs,fseekVal, babyLoopSize, babyLoopSize2, babyLoopSize3, babyLoopSize4;
MPI_Init(NULL,NULL);
MPI_Comm_size(MPI_COMM_WORLD, &world_size);
MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
cout << " my rank is " << my_rank << "\n";
importFiles();
cout << " my rank is " << my_rank << " I know that enron's doc size is " << enronInfo[0] << "\n";
if(my_rank == 0){
getUserResponse();
}
MPI_Barrier(MPI_COMM_WORLD);
babyLoopSize = enronInfo[0] / (world_size - 1);
babyLoopSize2 = nipsInfo[0] / (world_size - 1);
babyLoopSize3 = kosInfo[0] / (world_size - 1);
babyLoopSize4 = nytInfo[0] / (world_size - 1);
//cout << " my rank is " << my_rank << " I know that enron's doc size is " << enronInfo[0] << " and that my babyLoopSize for enron is " << babyLoopSize << "\n";
//cout << " my rank is " << my_rank << " I know that qNum is " << qNum << "\n";
MPI_Bcast(&qNum, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Bcast(&firstSource, 2, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Bcast(&secondSource,3, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Bcast(&enteredWordChar,4, MPI_CHAR, 0, MPI_COMM_WORLD);
if(qNum == 1){
if(firstSource == 1){
if(my_rank == 0){
int startVal = 0;
int z = 1;
for(int i = 1; i <= enronInfo[0]; i++){
if(z == world_size){
z = 1;
}
startVal = getFseekVal(i, firstSource);
MPI_Send(&startVal, 1, MPI_INT, z, i, MPI_COMM_WORLD);
}
if(my_rank != 0){
int startVal;
for(int i = 0; i<=babyLoopSize; i++){
MPI_Recv(&startVal, 1, MPI_INT, 0, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
}
}
MPI_Barrier(MPI_COMM_WORLD);
}
}
MPI_Finalize();
}
答案 0 :(得分：1)
MPI_Send通常是阻止命令，请参阅here：
此例程可能会阻止，直到收到消息 目的地过程。
这意味着每次在主进程上运行MPI_Send时，相应的从进程必须在主进程可以继续之前运行MPI_Recv。通过包含第一个MPI_Barrier行，您告诉每个从属设备等待主设备在让从设备接收数据之前完成所有数据的发送，但由于MPI_Send的阻塞性质，主设备永远不会从第一次致电返回MPI_Send。
对于你的问题，我建议先把它制成小块。编写代码来回答每个子问题：
// Determine how many workers we have
int nWorkers = ...;
// Determine where in the file each worker should start
// If we store each location in an array we can make use of
// another MPI command latter
int aStartingLocs[nWorkers] = {...};
// Distribute starting locations to each worker
int nMyStart;
MPI_Scatter(aStartingLocs, 1, MPI_INT, //< Things to send
&nMyStart, 1, MPI_INT, //< Recieved value
...);
// Our starting location is stored in nMyStart
// TODO: Use starting location to compute results
double dResult = ...;
// We can use MPI_Gather to send the values back to master
double aResults[nWorkers];
MPI_Gather(&dResult, 1, MPI_DOUBLE, //< What we are sending
aResults, 1, MPI_DOUBLE, //< Where to store the result
...);
// Now we can use the result how we choose
if (bIAmMaster)
{
// TODO: Use the results
}
上面只是一个大纲（半伪代码/评论），但希望你能够将它作为指南。
我暂时没有使用过MPI，因此您应该明确检查MPI_Scatter和MPI_Gather的语法。 Check out the first link that came up on Google.
如果您需要分散一些不能被您可以使用MPI_Scatterv和MPI_Gatherv的工人数量整除的项目，请参阅man page。
如果您如此倾向于尝试实施自己的MPI_Scatter(v)版本，我会回想起HPC的具体做法。但是，大多数情况下，使用库函数可能更容易/更好。